1. Field of the Invention
This invention relates generally to automated library systems and, more particularly, to an automated data cartridge storage library system that includes a buffered access system for automatically loading and unloading data storage cartridges.
2. Related Art
The computer and information industry has evolved to the point where it is necessary and desirable to have a computer facility operate without human operators. Typically, an automated storage library system has been used to store and retrieve data with a robotic media-handling device. These automated library systems typically have library modules with a magnetic tape cartridge capacity of approximately 6,000 cartridges. As a result, there is a continual need to feed or retrieve the magnetic tape cartridges from the library system.
One conventional technique used to load and unload magnetic tape cartridges from a storage library is to configure the storage library with a door to enable an operator to physically enter the device. This enables the operator to climb into the storage library to manually load and unload the cartridges. To provide the operator safe access, the operation of the automated system must be stopped, and all production ceased. In addition, the operator must carry up to 6,000 cartridges through the door and sequentially place each one into its individual storage cell.
One drawback to this approach is that it reduces the operating time of the storage library by the loading/unloading time. In addition, this technique reduces the system integrity due to the high potential for errors associated with the manual placement of cartridges in their respective storage cells. Also, providing operator access to the entire storage library beyond that needed to load/unload particular cartridges reduces the security of the system.
Another conventional technique is to implement a smaller access port which consists of a bank of cartridge slots (cells) mounted to a panel which rotates out from inside the storage area to present itself to the operator on the outside of the library module. This technique does not impact the operational time of the device since the robot mechanism does not have to be stopped during the loading/unloading process. However, this technique is timely since the loading module must be opened and closed 100 to 200 times, depending on the number of data storage cartridges held by the panel, to accomplish a full capacity load. In addition, the storage capacity of the library module is reduced by the number of fixed storage cells replaced by the panel. Lastly, each of the panels have to be monitored with sensing hardware to prevent the robot mechanism from accessing the storage cells on a panel while it is in the open position. An example of a storage library implementing such a technique is described in U.S. Pat. No. 4,779,151 to Lind, et al.
A third conventional solution is to implement the storage library with fixed pass-thru panels which enable the operator to pass the cartridges to the interior of the library module in a manner similar to a post office box. In such a system, the cartridges could be loaded and unloaded from the outside of the library module at any time while the robot arm simultaneously accesses the storage cells from the interior of the storage library.
The technique does not require the storage library to stop operation. However, the cartridge identification labels have to face the inside of the storage library so that the robot visual system can scan them. This enables the library module to catalog the cartridges and establish its database. As a result, the cartridge ID labels are unreadable to an operator accessing the storage cells from the opposite side. Furthermore, to prevent the cartridges from sliding out of their storage cells, a latching mechanism has to be employed to hold the cartridges when the outside panel is opened. Lastly, this technique drastically reduces system integrity due to the manual access of the cartridges.
What is needed is a system and method for automatically loading and unloading media from a storage library without human intervention and without interfering with the operation of the robotic arm. The system also needs to maintain system integrity and security, while not decreasing the overall storage capacity of the library system.